Oscillometry, also known as Forced Oscillation Technique (FOT), is a noninvasive method to measure how easy is for the air to move in and out the respiratory system. Such “impediment” is quantified by combining the force used to move the air (i.e. the pressure) with the amount of air that actually has been displaced (i.e. air flow) and calculating the RESPIRATORY IMPEDANCE.
Air can be prevented to move in and out the respiratory system by several factors. Airway obstructions, reduced lung parenchyma elasticity, peripheral obstruction or alveolar collapse are all elements that will produce an increase of the RESPIRATORY IMPEDANCE.
Mathematically it is possible to separate such contributions by splitting IMPEDANCE in into RESPIRATORY RESISTANCE (Rrs) and REACTANCE (Xrs).